Power management for electrochromic window networks

ABSTRACT

Various embodiments herein relate to networks of electrochromic windows. The networks may be configured in particular ways to minimize the likelihood that the windows on the network draw more power than can be provided. The network may include particular hardware components that provide additional power to windows as needed. The network may also be configured to adjust how the windows therein transition to prevent overloading the network. The techniques described herein can be used to design networks of electrochromic windows that are undersized when considering the amount of power that would be needed to simultaneously transition all the windows on the network using normal transition parameters, while still allowing simultaneous transitions to occur.

CROSS REFERENCE TO RELATED APPLICATIONS

An Application Data Sheet is filed concurrently with this specificationas part of the present application. Each application that the presentapplication claims benefit of or priority to as identified in theconcurrently filed Application Data Sheet is incorporated by referenceherein in its entirety and for all purposes.

BACKGROUND

Electrochromism is a phenomenon in which a material exhibits areversible electrochemically-mediated change in an optical property whenplaced in a different electronic state, typically by being subjected toa voltage change. The optical property is typically one or more ofcolor, transmittance, absorbance, and reflectance. One well knownelectrochromic material, for example, is tungsten oxide (WO₃). Tungstenoxide is a cathodic electrochromic material in which a colorationtransition, transparent to blue, occurs by electrochemical reduction.

Electrically switchable windows, whether electrochromic or otherwise,may be used in buildings to control transmission of solar energy.Switchable windows may be manually or automatically tinted and clearedto reduce energy consumption, by heating, air conditioning and/orlighting systems, while maintaining occupant comfort.

Only recently have designers begun developing control and power systemsfor buildings having many electrically tintable windows. As aconsequence, many developments are required before such systems canoperate reliably and approach their potential.

SUMMARY

Various embodiments herein relate to power distribution networks forelectrochromic windows, and methods of forming such networks. In manycases, a power distribution network is capable of managing the supply ofpower and/or the demand for power to avoid over-taxing the network. Insome cases, a network may be capable of delivering power to windows at ahigher rate than power is delivered to the network. Local energy storageunits such as energy wells may be provided to accomplish this feature.In these or other cases, a power distribution network may be capable ofadjusting transition parameters on the electrochromic windows to reducea demand for power. In some cases, a network may be modified to includeadditional electrochromic windows with minimal disruption to thenetwork.

In one aspect of the disclosed embodiments, a network is provided, thenetwork including: (a) two or more window assemblies, each including: atleast one electrochromic pane, and a window controller for drivingoptical transitions on the electrochromic pane; (b) a power supplyelectrically connected with the window assemblies; and (c) one or moreenergy wells electrically connected with the power supply and with thewindow assemblies, wherein the one or more energy wells are providedelectrically downstream from the power supply and electrically upstreamfrom at least one of the window assemblies, where the network isconfigured to transfer power from the energy wells to the windowassemblies when the window assemblies collectively demand a greateramount of power than can be provided by the power supply, and totransfer power from the power supply to the energy wells to recharge theenergy wells when the window assemblies collectively demand a loweramount of power than can be provided by the power supply.

In certain implementations, the power supply may be a class 2 powersupply. In other implementations, the power supply may be a class 1power supply. The energy well may include a supercapacitor in somecases. In these or other cases, the energy well may include arechargeable battery. The energy well may have an energy storagecapacity sufficient to simultaneously drive an optical transition in atleast 2 window assemblies on the network. In some cases, a number ofenergy wells may be provided. In one example, at least one energy wellis provided per every 4 window assemblies on the network. The energywells may be integrated into the window assemblies in some embodiments.

In various embodiments, the network may further include a networkcontroller and/or a master controller communicatively coupled with thewindow controller of each of the two or more window assemblies. Thenetwork controller and/or master controller may be configured to causeone or more of the window assemblies to undergo a first opticaltransition using a first set of transition parameters when a firstcondition is present, and to cause one or more of the window assembliesto undergo a second optical transition using a second set of transitionparameters when a second condition is present, the first condition beingdifferent from the second condition.

In some cases, the first condition may relate to a condition where thewindow assemblies collectively demand relatively more power, and thesecond condition may relate to a condition where the window assembliescollectively demand relatively less power. The first condition mayrelate to a situation where, e.g., the window assemblies directed totransition would collectively demand, if transitioned using the secondset of transition parameters, either (i) more power than can be providedby the power supply and the one or more energy wells, or (ii) more thana certain fraction of the power that can be provided by the power supplyand the one or more energy wells.

The second condition may relate to a situation where, e.g., certainzones of windows or an entire group or network of windows in the networkrequire less power to transition, e.g., when the window assembliesdirected to transition would collectively demand, if transitioned usingthe second set of transition parameters, either (i) less power than canbe provided by the power supply and the one or more energy wells, or(ii) less than a certain fraction of the power that can be provided bythe power supply and the one or more energy wells. In certain cases whenthe second condition is present, power from the power supply may bedirected to recharge the one or more energy wells. In these or otherembodiments, when the second condition is present, power from the powersupply may be used for other purposes off the network, e.g., the powermay be used to feed the local power grid or other building systems. Insome cases the network, by virtue of its energy wells, can supply extrapower required by the windows, alone or in combination with the powersupply(ies) in the network. The network may further include a sensor formeasuring voltage and/or current. The measured voltage and/or currentmay relate to the voltage and/or current delivered from or to anycomponent on the network.

In a further aspect of the disclosed embodiments, a network is provided,the network including: (a) two or more window assemblies, eachincluding: at least one electrochromic pane, and a window controller fordriving optical transitions on the electrochromic pane; (b) one or morepower sources including at least a primary power supply and, optionally,one or more energy wells, the power source(s) being electricallyconnected with the window assemblies; and (c) a network controllerand/or master controller communicatively coupled to the windowcontrollers, where the network controller and/or master controllerincludes instructions to prevent the window assemblies from collectivelydemanding more power than can be delivered by the power source(s), wherethe instructions include: (i) prioritizing transition of certain windowassemblies such that certain window assemblies transition before otherwindow assemblies, and/or (ii) using a modified set of drive transitionparameters for driving optical transitions on the window assemblies whenthe power needed to transition the window assemblies collectivelyexceeds a threshold, where the modified set of drive transitionparameters is different from a first set of drive transition parametersused to drive optical transitions on the window assemblies when thepower needed to transition the window assemblies is collectively underthe threshold.

In certain implementations, the network controller and/or mastercontroller may be configured to stagger the transitions of the windowassemblies over time. In these or other implementations, the networkcontroller and/or master controller may be configured to use themodified set of drive transition parameters, where the modified set ofdrive transition parameters results in a lower collective power use, perunit of time, compared to the first set of drive transition parameters.In some such implementations, each of the first set and the modified setof drive transition parameters may include a ramp to drive voltage rate,where the ramp to drive voltage rate of the modified set of drivetransition parameters has a lower magnitude than the ramp to drivevoltage rate of the first set of drive transition parameters. In theseor other implementations, each of the first set and the modified set ofdrive transition parameters may include a drive voltage, where the drivevoltage of the modified set of drive transition parameters has a lowermagnitude than the drive voltage of the first set of drive transitionparameters. In various embodiments, the one or more power sources mayhave a maximum collective power output, where simultaneously drivingoptical transitions on two or more window assemblies using the first setof drive transition parameters would involve a greater amount of powerthan the maximum collective power output of the one or more powersources. In certain embodiments, the one or more energy wells mayprovide power to the window assemblies at times when the powercollectively demanded by the window assemblies is above a secondthreshold, and may recharge from the primary power supply when the powercollectively demanded by the window assemblies is below the secondthreshold, where the second threshold is based on a maximum power thatcan be delivered by the primary power supply. The energy wells mayinclude supercapacitors in some cases. In these or other cases, theenergy wells may include rechargeable batteries.

In another aspect of the disclosed embodiments, a network is provided,the network including: (a) two or more window assemblies, eachincluding: at least one electrochromic pane, a window controller fordriving optical transitions on the electrochromic pane, and asupercapacitor for powering optical transitions on the electrochromicpane; (b) a power supply electrically connected with the windowassemblies, wherein the network is configured to transfer power from thesupercapacitors to the electrochromic panes when the window assembliescollectively demand a greater amount of power than can be provided bythe power supply, and to transfer power from the power supply to thesupercapacitors to recharge the supercapacitors when the windowassemblies collectively demand a lower amount of power than can beprovided by the power supply. In some embodiments, the supercapacitorsmay be part of the window controllers.

In another aspect of the disclosed embodiments, a network is provided,the network including: (a) two or more window assemblies, eachincluding: at least one electrochromic pane, and a window controller fordriving optical transitions on the electrochromic pane; (b) a powersupply electrically connected with the window assemblies; and (c) one ormore energy wells electrically connected with the power supply and withthe window assemblies, wherein the network is configured to: (i)transfer power from the energy well(s) to the window assemblies when thewindow assemblies collectively demand a greater amount of power than canbe provided by the power supply, (ii) transfer power from the powersupply to the energy well(s) to recharge the energy well(s) when thewindow assemblies collectively demand a lower amount of power than canbe provided by the power supply, and (iii) transfer power from theenergy well(s) to a power cable electrically positioned between theenergy well(s) and the power supply when a command is received directingthe network to do so.

In yet another aspect of the disclosed embodiments, a method ofmodifying a network of electrochromic windows is provided, the methodincluding: installing one or more additional window assemblies in apre-existing network of window assemblies, the pre-existing networkincluding: two or more window assemblies, each window assembly includingat least one electrochromic pane, two or more window controllers, eachwindow controller electrically connected to one of the windowassemblies, and one or more power supplies collectively having a maximumpower output, where before installation of the one or more additionalwindow assemblies, a power used to simultaneously drive opticaltransitions on all of the window assemblies using a first set of drivetransition parameters is collectively below the maximum power output,where after installation of the one or more additional windowassemblies, a power used to simultaneously drive optical transitions onall of the window assemblies using the first set of drive transitionparameters collectively exceeds the maximum power output, and whereafter installation of the one or more additional window assemblies, thenetwork can execute a command to simultaneously drive opticaltransitions on all of the window assemblies without demanding a level ofpower from the one or more power supplies that exceeds the maximum poweroutput.

In certain embodiments, the method may further include installing one ormore energy wells in electrical communication with (a) the one or morepower supplies and (b) the two or more window assemblies of thepre-existing network and/or the one or more additional windowassemblies. In other implementations, the method does not includeinstallation of any additional power sources. In some implementations,the pre-existing network may further include one or more energy wells inaddition to the one or more power supplies. In various embodiments,before installation of the one or more additional window assemblies, thenetwork may be configured to use a first set of drive transitionparameters to drive optical transitions on the window assemblies, andafter installation of the one or more additional window assemblies, thenetwork may be configured to use a modified set of drive transitionparameters to drive optical transitions on the window assemblies, wherethe modified set of drive transition parameters results in a lower powerusage per window assembly, per unit time, compared to the first set ofdrive transition parameters.

These and other features and advantages of the disclosed embodimentswill be described in further detail below, with reference to theassociated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description can be more fully understood whenconsidered in conjunction with the drawings in which:

FIG. 1 illustrates a cross sectional view of an electrochromic deviceaccording to certain embodiments.

FIG. 2 is a diagram of components of a power distribution andcommunication network for controlling functions of one or more tintablewindows of a building.

FIG. 3 presents a power distribution network for electrochromic windowsaccording to certain implementations.

FIG. 4 presents a power distribution network for electrochromic windowsthat includes an additional power delivery line.

FIG. 5 presents a power distribution network for electrochromic windowsthat includes an additional power delivery line and additional energystorage units.

FIG. 6 shows current and voltage profiles that may be used to drive anoptical transition in an electrochromic window in various embodiments.

FIGS. 7 and 8 present schematic views of power distribution networksthat can also operate as communication networks for electrochromicwindows according to various embodiments.

FIGS. 9-11 present views of power distribution networks forelectrochromic windows configured according to a number of embodiments.

FIG. 12 presents a representation of a window controller and associatedcomponents according to certain embodiments.

DETAILED DESCRIPTION Electrochromic Devices

Various embodiments disclosed herein relate to improved window controland/or network configurations for electrochromic windows. The disclosednetwork configurations and window control methods can in many cases beused to minimize the overall power capacity of a power distributionnetwork and thereby reduce the capital and/or operating costs of anelectrochromic window installation. These benefits can be achieved by,for example, minimizing the amount of wiring needed to connect all therelevant windows, minimizing loss of power over the power deliverylines, maintaining the network and equipment thereon within a particularclass/rating, and/or minimizing the number of control boxes used topower the windows. One advantage of the disclosed techniques is that anetwork of electrochromic windows can be designed to operate at arelatively lower peak input power, which may avoid the need for moreexpensive infrastructure and equipment. Another advantage is thatnetworks designed according to the disclosed techniques are moreflexible/adaptable, and can therefore, e.g., 1) accept additionalwindows (after an initial installation) with minimal rewiring andinfrastructure changes, 2) manage power delivery on the network bydynamically changing the distribution of available power to suit varyingdemand, 3) deliver power to electrochromic windows in the network and/orexternal systems such as power grids or other building systems, and 4)store power in energy wells of the network, which allows, e.g.,continued use of the electrochromic windows during power shortages e.g.,when power supplies in the network fail and/or external power to thenetwork fails or is diminished, and less substantial cabling andreliance on external power for switching windows in the network.

A schematic cross-section of an electrochromic device 100 in accordancewith some embodiments is shown in FIG. 1. The electrochromic deviceincludes a substrate 102, a conductive layer (CL) 104, adefect-mitigating insulating layer (DMIL) 105, an electrochromic layer(EC) 106 (sometimes also referred to as a cathodically coloring layer ora cathodically tinting layer), an ion conducting layer or region (IC)108, a counter electrode layer (CE) 110 (sometimes also referred to asan anodically coloring layer or anodically tinting layer), and aconductive layer (CL) 114. Elements 104, 105, 106, 108, 110, and 114 arecollectively referred to as an electrochromic stack 120. A voltagesource 116 operable to apply an electric potential across theelectrochromic stack 120 effects the transition of the electrochromicdevice from, e.g., a clear state to a tinted state. In otherembodiments, the order of layers is reversed with respect to thesubstrate. That is, the layers are in the following order: substrate,conductive layer, defect-mitigating-insulating layer, counter electrodelayer, ion conducting layer, electrochromic material layer, conductivelayer.

In various embodiments, the ion conductor region 108 may form from aportion of the EC layer 106 and/or from a portion of the CE layer 110.In such embodiments, the stack 120 may be deposited to includecathodically coloring electrochromic material (the EC layer) in directphysical contact with an anodically coloring counter electrode material(the CE layer). The ion conductor region 108 (sometimes referred to asan interfacial region, or as an ion conducting substantiallyelectronically insulating layer or region) may then form where the EClayer 106 and the CE layer 110 meet, for example through heating and/orother processing steps, as explained in U.S. Pat. No. 8,765,950, whichis herein incorporated by reference in its entirety.

In various embodiments, one or more of the layers shown in FIG. 1 may bedeposited to include two or more sublayers. In one example, the EC layer106 and/or the CE layer 110 may be deposited to include two or moresublayers. The sublayers within a given layer may have differentcompositions and/or morphologies. The sublayers may be included topromote formation of the ion conducting region 108 and/or to tunevarious properties of the electrochromic device 100.

Further, an electrochromic device may include one or more additionallayers not shown in FIG. 1. Such layers may improve optical performance,durability, hermeticity, and the like. Examples of additional layersthat may be used include, but are not limited to, anti-reflectivelayers, additional defect-mitigating insulating layers (which may beprovided within or between any of the layers shown in FIG. 1), and/orcapping layers. The techniques disclosed herein are applicable to a widevariety of electrochromic device designs.

In certain embodiments, the electrochromic device reversibly cyclesbetween a clear state and a tinted state. In the clear state, apotential is applied to the electrochromic stack 120 such that availableions in the stack that can cause the electrochromic material 106 to bein the tinted state reside primarily in the counter electrode 110. Whenthe potential on the electrochromic stack is reversed, the ions aretransported across the ion conducting layer 108 to the electrochromicmaterial 106 and cause the material to enter the tinted state.

It should be understood that the reference to a transition between aclear state and tinted state is non-limiting and suggests only oneexample, among many, of an electrochromic transition that may beimplemented. Unless otherwise specified herein, whenever reference ismade to a clear-tinted transition, the corresponding device or processencompasses other optical state transitions such asnon-reflective-reflective, transparent-opaque, etc. Further, the terms“clear” and “bleached” refer to an optically neutral state, e.g.,untinted, transparent or translucent. Still further, unless specifiedotherwise herein, the “color” or “tint” of an electrochromic transitionis not limited to any particular wavelength or range of wavelengths. Asunderstood by those of skill in the art, the choice of appropriateelectrochromic and counter electrode materials governs the relevantoptical transition.

In certain embodiments, all of the materials making up electrochromicstack 120 are inorganic, solid (i.e., in the solid state), or bothinorganic and solid. Because organic materials tend to degrade overtime, inorganic materials offer the advantage of a reliableelectrochromic stack that can function for extended periods of time.Materials in the solid state also offer the advantage of not havingcontainment and leakage issues, as materials in the liquid state oftendo. It should be understood that any one or more of the layers in thestack may contain some amount of organic material, but in manyimplementations one or more of the layers contains little or no organicmatter. The same can be said for liquids that may be present in one ormore layers in small amounts. It should also be understood that solidstate material may be deposited or otherwise formed by processesemploying liquid components such as certain processes employing sol-gelsor chemical vapor deposition. Information related to the various layersof the electrochromic device, including information related to thedeposition thereof, is presented in U.S. application Ser. No.12/645,111, filed Dec. 22, 2009, and titled “FABRICATION OF LOWDEFECTIVITY ELECTROCHROMIC DEVICES,” which is herein incorporated byreference in its entirety.

Electrochromic devices can be incorporated into insulated glass units(IGUs) having two or more panes, typically separated by a spacer andsealed together through various sealing components. In one example, anIGU includes a first pane having an electrochromic device depositedthereon, a second pane (which may or may not have an electrochromicdevice thereon), a spacer positioned between the panes and proximate theperiphery of the panes, a primary seal between the spacer and each pane,and a secondary seal that surrounds the spacer and primary seals. TheIGU may be installed in a frame. The IGU may also include wiring topower the electrochromic device, various sensors, a window controllerfor controlling transitions of the electrochromic device, and othercomponents. Electrochromic IGUs are further discussed and described inU.S. Pat. No. 8,213,074, and in U.S. patent application Ser. No.14/951,410, filed Nov. 24, 2015, and titled “SELF-CONTAINED EC IGU,”each of which is herein incorporated by reference in its entirety.

Networks Introduction

Two or more electrochromic windows may be connected on a network. Thenetwork may be used to distribute power and/or controlinformation/communication to the various windows in the network. Anumber of different network configurations are possible.

FIG. 2 is a block diagram of components of a window network system 200for controlling functions (e.g., transitioning to different tint levels)of one or more tintable windows at a site (e.g., a building), accordingto various embodiments. Although the description of FIG. 2 focusesprimarily on distribution of control information, it should beunderstood that some or all of the network shown may also serve todistribute power. In sections of the communications network that overlapwith the power distribution network, a single conductor may be used todeliver power (as in power-line communications), or separate lines maybe used to deliver power and communications, though infrastructure suchas conduits may be shared between these separate lines. System 200 maybe one of the systems managed by a window system through a buildingmanagement system (BMS) or may be managed directly by a window systemand/or operate independently of a BMS.

System 200 includes a window control system 202 that can send controlsignals to the tintable windows to control their functions. System 200also includes a network 210 in electronic communication with windowcontrol system 202, and a power source (not shown) for providing powerto the individual components on the network. Control logic andinstructions for controlling functions of the tintable window(s), and/orsensor data may be communicated to the window control system 202 throughthe network 210. Network 210 can be a wired or a wireless network (e.g.,a cloud network). In some embodiments, network 210 may be incommunication with a BMS (e.g., over an API) to allow the BMS to sendinstructions for controlling the tintable window(s) through network 210to the tintable window(s) in a building. In some cases, the BMS may bein communication with the window system to receive instructions forcontrolling the tintable window(s) from the window system. In otherembodiments, network 210 may be in communication with a window system toallow the window system to send instructions for controlling thetintable window(s) through network 210 to the tintable window(s) in abuilding. In certain embodiments, the window control system 202 and/orthe master controller 203 are designed or configured to communicate withthe window system or a component thereof such as a data warehouse.

System 200 also includes EC devices 250 of the tintable windows and wallswitches 290, which are both in electronic communication with windowcontrol system 202. In this illustrated example, window control system202 can send control signals to EC device(s) 250 to control the tintlevel of the tintable windows having the EC device(s) 250. Each wallswitch 290 is also in communication with EC device(s) 250 and windowcontrol system 202. An end user (e.g., occupant of a room having thetintable window) can use the wall switch 290 to control the tint leveland other functions of the tintable window having the EC device(s) 250.

In FIG. 2, window control system 202 is depicted as a distributednetwork of window controllers including a master controller 203, aplurality of network controllers 205 in communication with the mastercontroller 203, and multiple pluralities of end or leaf windowcontrollers 240. Each plurality of end or leaf window controllers 240 isin communication with a single network controller 205. Although windowcontrol system 202 is illustrated as a distributed network of windowcontrollers, window control system 202 could also be a single windowcontroller controlling the functions of a single tintable window inother embodiments. Each of the window controllers in the distributednetwork of FIG. 2 may include a processor (e.g., microprocessor) and acomputer readable medium (e.g., a memory device configured to storedigital information) in electrical communication with the processor.

In FIG. 2, each leaf or end window controller 240 is in communicationwith EC device(s) 250 of a single tintable window to provide power andcontrol the tint level of that tintable window in the building. In thecase of an IGU, the leaf or end window controller 240 may be incommunication with EC devices 250 on multiple lites of the IGU tocontrol the tint level of the IGU. In other embodiments, each leaf orend window controller 240 may be in communication with a plurality oftintable windows. The leaf or end window controller 240 may beintegrated into the tintable window or may be separate from the tintablewindow that it controls.

Each wall switch 290 can be operated by an end user (e.g., occupant ofthe room) to control the tint level and other functions of the tintablewindow in communication with the wall switch 290. The end user canoperate the wall switch 290 to communicate control signals to the ECdevices 250 in the associated tintable window. These signals from thewall switch 290 may override signals from window control system 202 insome cases. In other cases (e.g., high demand cases), control signalsfrom the window control system 202 may override the control signals fromwall switch 290. Each wall switch 290 is also in communication with theleaf or end window controller 240 to send information about the controlsignals (e.g., time, date, tint level requested, etc.) sent from wallswitch 290 back to window control system 202. In some cases, wallswitches 290 may be manually operated. In these or other cases, wallswitches 290 may be wirelessly controlled by the end user using a remotedevice (e.g., cell phone, tablet, etc.) sending wireless communicationswith the control signals, for example, using infrared (IR), and/or radiofrequency (RF) signals. In some cases, wall switches 290 may include awireless protocol chip, such as Bluetooth, EnOcean, WiFi, Zigbee, LiFi,and the like. Briefly, LiFi refers to Light Fidelity, which is abidirectional, high-speed and networked wireless communicationtechnology similar to WiFi. LiFi utilizes a light signal (e.g., visiblelight, infrared light, near-ultraviolet light, etc.) to conveyinformation wirelessly. The light signal may be sufficiently rapidand/or dim for human perception, though such signals can be easilyperceived by appropriate receivers. In some cases, the LiFi signal maybe generated by one or more light emitting diode (LED), which may becoated with (or otherwise include) a material that allows for high datatransmission rates. Example materials may include perovskites. Oneparticular example material is cesium lead bromide (CsPbBr₃), which maybe provided in nanocrystalline form. In various embodiments, controlsignals (e.g., between a wall switch 290 and a component on the windowcontrol system 202 such as an end or leaf window controller 240, orbetween any of the components on the window control system 202) may betransferred via LiFi. To this end, any of the switches, controllers,electrochromic windows, and other components of the system may includeappropriate transmitters and/or receivers for transmitting and/orreceiving communication signals, including Bluetooth, EnOcean, WiFi,Zigbee, LiFi, and similar signals. Although wall switches 290 depictedin FIG. 2 are located on the wall(s), other embodiments of system 200may have switches located elsewhere in the room.

Wireless communication between, for example, master and/or networkcontrollers and end window controllers offers the advantage of obviatingthe installation of hard communication lines. This is also true forwireless communication between window controllers and BMS. In oneaspect, wireless communication in these roles is useful for datatransfer to and from electrochromic windows for operating the window andproviding data to, for example, a BMS for optimizing the environment andenergy savings in a building. Window location data as well as feedbackfrom sensors are synergized for such optimization. For example, granularlevel (window-by-window) microclimate information is fed to a BMS inorder to optimize the building's various environments. Logic forimplementing the methods described herein, including but not limited tomethods for prioritizing transition of certain windows over others, andmethods for altering the transition parameters for windows transitioningunder certain limited power availability conditions, may be provided onany of the controllers and control systems described herein. Forinstance, such logic may be provided on a window control system, amaster controller, a network controller, a window controller, or somecombination thereof. In various embodiments, there is a communicativeconnection between a window controller, which controls transitions onone or more electrochromic windows, and a network controller and/orwindow controller, for example as illustrated in FIG. 2. Logic forinitiating and controlling transitions on one or more electrochromicwindows may be provided on the master controller and/or networkcontroller, which may feed the instructions to the window controller forexecution on the one or more electrochromic windows. In one embodiment,the logic is provided on one or more network controllers, which feed theinstructions to the window controllers. In another embodiment, the logicis provided on one or more master controllers, which feed theinstructions to the network controllers, which feed the instructions tothe window controllers. Generally speaking, there may be a communicativerelationship between a window controller and one or more higher level orcentral controllers (which may be implemented as one or more networkcontrollers and/or one or more master controllers, for instance). Thiscommunicative relationship may be used to transfer control informationamong the various controllers, as desired.

The references to a BMS in the above description can be replaced in someor all instances with references to a smart thermostat service or otherhome appliance service such as NEST. The communication between thewindow system and the BMS or home appliance service can be via an API asdescribed above.

Power Considerations

One of the primary considerations when designing a network ofelectrochromic windows is the power requirements of such windows. Thepower delivered over the network will be greatest if/when all or a largeportion of the windows on the network are directed to undergo an opticaltransition at the same time. Where this is the case, the network may beunderstood to be delivering “peak power.” Peak power delivery occursrelatively rarely on most systems, and the power used by a system at anytime may be on the order of about 10% of the peak power. This is becauserarely do all the windows need to transition at the same time, e.g.,different zones of windows on different sides of a building or differentelevation on the same side will often be tinted at different times.However, because there may be occasions where peak power delivery iswanted or needed, a power distribution network is conventionallydesigned to deliver such power on demand. Examples where peak powerdelivery may be needed include cases where there is a security situation(e.g., where all interior and/or exterior windows may be tinted toprevent a potential security threat from seeing into/through thewindows, or where all interior and/or exterior windows may be madetransparent to minimize the opportunity for a potential security threatto hide), cases where windows are simultaneously tinted or untinted todemonstrate the functionality of the windows/building (e.g., during acommissioning phase after installation), cases where electrochromicwindows are used in an artistic exhibition, cases where all or manybuilding windows must rapidly transition to a protected state (e.g., allclear) in anticipation of an emergency situation where a local powerutility cannot keep up with demand, etc. Such emergencies may relate toblackouts, brownouts, etc. Outside of such situations, peak powerdelivery is typically not needed, and a relatively lower amount of poweris delivered to the electrochromic windows on the network. Moreover,conventional electrochromic window installations are designed with a setnumber of windows in mind, i.e., the power distribution network for thewindows is designed and built for a specific number of windows that areinitially installed, thus it is not designed for later expansion of thenumber of windows connected to the network. As well, conventionalelectrochromic window installations may include networks that are “overengineered,” i.e., designed with peak load in mind, while peak load israrely a reality over the life of the system. Embodiments describedherein allow for more modest power distribution networks that, whilestill able to provide peak power delivery, generally require less costlyinfrastructure than convention systems and are more flexible thanconventional systems when it comes to powering schemes.

Even if there is not a specific need for the system to transition allthe windows at the same time, an operator may direct the system to doso. Therefore, the network should be capable of executing an instructionto simultaneously drive an optical transition in all the electrochromicwindows. The execution of this instruction may involve actuallytransitioning all the windows at once, or it may involve directing thewindows to change sequentially within a short period of time.

Power management for the network involves balancing the supply anddemand of available power. In various embodiments, the supply and/ordemand of available power may be controlled in a way that minimizes themaximum rate at which power is input to the system. The disclosedtechniques can be used to design a power distribution network forelectrochromic windows that has lower power input requirements thanwould otherwise be required. These techniques may minimize cost, forexample by avoiding the need for equipment designed to operate at higherpeak power delivery, minimizing the amount of wiring, etc.

Managing Supply of Available Power

One of the techniques for managing power distribution over a network ofelectrochromic windows is to manage the supply of energy available fordriving optical transitions. In some conventional networks, severalelectrochromic windows may be driven by a single control panel(sometimes also referred to as control boxes, power supplies, powersources, etc.), which typically provides all the power used to driveoptical transitions on the windows. A building may be equipped withmultiple control panels, which may deliver both power and controlinformation. In some cases there may be one control panel per floor, orone control panel per region of the building. The number ofelectrochromic windows that may be driven by a single control panel maybe determined by the power needed to drive each window and the maximumpower deliverable by the control panel. The number of electrochromicwindows that may be driven on a single power line may further depend online loss, which is affected by the voltage being carried over the lineand the distance of the line. Where a set of windows draws (or attemptsto draw) a greater amount of power than can be delivered, the circuit onwhich the windows are placed may be tripped and the window transitionsmay fail.

FIG. 3 presents a simplified view of a power distribution network 300including a series of electrochromic windows 301-306 each driven by acontrol panel 310. A trunk line 315 connects all of the windows 301-306to the control panel 310, and may carry power, communicationinformation, or both. In some cases, the power required to drivesimultaneous optical transitions in the windows 301-306 may exceed thepower that can be delivered by the control panel 310 over a single line.As such, an additional power line may be provided to power certainwindows. This additional power line may be required as additionalelectrically switchable windows are added after an initial installation.

FIG. 4 presents a simplified view of a network 400 that includes aseries of electrochromic windows 401-406, each driven by control panel410. Here, two lines are provided to bring power to the windows fromcontrol panel 410. A first line 415 may power a first set of windows401-403, and a second line 416 may power a second set of windows404-406. However, network 400 is still limited by the power output ofthe control panel 410. The lines 415 and 416 may be segmented withrespect to power delivery, with the different lines powering differentsets of windows, as shown. Communication (e.g., control information) maybe transmitted in any fashion. In one example communication occurswirelessly. In another example, communication may be transmitted throughseparate lines not shown in the figures. In other cases, power-linecommunications protocols may be used to transmit both power and dataover a single conductor line. For example, line 415 may carry both powerand communications for all the windows 401-406, or for windows 401-403.In another example, line 415 may transmit communication information forwindows 401-406, and may transmit power for windows 401-403 (with line416 providing power for windows 404-406). In yet another example,communication may be transmitted through both lines 415 and 416. Each ofthe lines 415 and 416 may include multiple wires for carrying powerand/or communication.

In certain implementations, power storage units (often referred toherein as “energy wells”) may be provided along the power lines. In someexamples, the energy wells may be provided along a trunk line thatconnects two or more of the windows to a control panel or other powersource. The energy wells can provide power to drive optical transitionson one or more windows. The energy wells effectively increase the peakpower available for delivery by the system because energy can bedelivered from both the control panel(s) and the energy well(s)simultaneously. The energy wells can be recharged when there is excesspower available on the network (e.g., when the windows are not changingtint state such as night or when the power being used to drive thewindows is less than the power that can be delivered by the controlpanel or other power supply). Analogously, with energy wells in thepower distribution network, less total power is required for theincoming power to the system, because of the augmented power availablefrom the energy wells. Thus, wiring for the distribution network may beless or of smaller gauge and/or power requirements and/or have lessduplication or redundancy that otherwise might be necessary (e.g., asdescribed in relation to FIG. 4 (though some extra power lineconnections may be advantageous for other reasons in distributionnetworks with energy wells)).

One embodiment is a class 2 power network for electrochromic windows,where the power network includes one or more energy wells. The one ormore energy wells are distributed or otherwise located between the powersupply (often provided in the control panel) and the electrochromicwindows of the system. That is, the one or more energy wells aredownstream of the power supply and upstream of the electrochromicwindow, e.g., upstream of the electrochromic window controller orotherwise not part of the window assembly.

In conventional electrochromic window networks, power input into thenetwork closely corresponds in time and magnitude with power deliveredby the network. The power input into the network refers to the powerdrawn by the network from a main power source (e.g., via controlpanel(s) or other source(s) within the facility, in some cases from thepower grid). The power delivered by the network refers to the powerprovided to the individual windows/window controllers (and any relatedcomponents) to drive optical transitions on the windows (or in somecases, also including extra power that is supplied to other buildingsystems or to a power grid). In conventional electrochromic windownetworks, these are largely the same (except for losses occurring dueto, e.g., line loss). As such, the maximum power that can be deliveredto the windows is limited by the maximum power that can be input intothe system from the main power source. However, the use of energy wellsallows for these power transfers to be decoupled to some extent. In thisway, the maximum power delivered to the windows can exceed the maximumpower input into the system at a given time. Therefore, networks thatutilize energy wells can achieve a higher peak delivered power thansimilar networks that do not utilize such energy wells, and they can dothis without being “over engineered” (e.g., without using larger or morepower supplies than are needed using the methods/configurationsdescribed herein).

One advantage of the use of energy wells is that electrochromic windownetworks can be designed to operate at lower peak input power than wouldotherwise be required. The peak input power in such cases may be lowerthan the power required to simultaneously tint or untint all theelectrochromic windows on the network, while the peak output power maystill be sufficiently high to simultaneously tint or untint all thewindows. For example, though the described power networks are able todeliver peak power load to the windows of the system, the powersupply(ies) feeding the system may not be able to do so, and need not beable to do so. Further, power networks described may be configured todeliver greater than peak output, which allows for future expansion ofthe network of electrochromic windows, e.g., adding more windows to thesystem without having to upgrade the power network, and allows, e.g.,the system to transition all the windows in the system and supply extrapower to external systems if need be, at least for some period of time.The power network can be recharged during non-peak load periods. As usedherein, the term “power source” includes both power supplies (and anycomponent in which a power supply is provided, e.g., a control panel) inthe conventional sense, as well as the described energy wells.Conventional power supplies are electronic devices that supply electricenergy to an electrical load, and typically convert energy from one formof electrical energy to another. A power supply includes a power input,which receives energy from an energy source (e.g., the power grid), anda power output, which delivers energy to the load. The energy wells andpower supplies can provide the power for transitioning theelectrochromic windows as directed, either separately or together.Because the energy wells may be recharged via energy delivered from thepower supply(ies), the power supplies may also be considered powersources for the energy wells.

FIG. 5 presents a simplified view of a network 500 that includes aseries of electrochromic windows 501-506 connected by a first power line515 and a second power line 516. The power lines may be segmented asdescribed in relation to FIG. 4. Communication may occur through anyavailable means, for example as described in relation to FIG. 4. Twoenergy wells 520 and 521 are included in the embodiment of FIG. 5. Inone example, control panel 510 is only capable of simultaneouslypowering transitions in two windows per individual power line (invarious embodiments this number may be significantly higher). When acommand is received to simultaneously drive an optical transition in allof the windows 501-506, the control panel 510 may drive the transitionsby delivering power to windows 501 and 502 through the first power line515 and to windows 504 and 505 through the second power line 516. Powermay be delivered to window 503 by energy well 520, and to window 506 byenergy well 521. After the transition, the energy wells 520 and 521 maybe recharged, for example through power lines 515 and 516. In otherembodiments, the combination of power from control panel 510 and energywells 520 and 521 is used, collectively, to power the transitions ofwindows 501-506, i.e., the energy may be distributed to all the windowswithout any particular designation as to which source powers whichwindows. Thus, utilizing one or more power supplies (which may beprovided in control panels), with one or more energy wells, allows fordistributed power along a network, the distributed power may be utilizedin a number of ways.

In the embodiment of FIG. 5, all or nearly all of the windows mayundergo simultaneous optical transitions even though the control panel510 is not capable of providing sufficient power to drive thetransitions simultaneously by itself; the power network includes energywells and thus, collectively, the network has sufficient power. In someembodiments, the network is configured to use only power that isprovided from the energy wells, i.e., power supplies are specificallynot used to deliver power (even though such power supplies may bephysically present). Such power delivery from the energy wells alone maybe particularly useful during power outages (which may be intentional orunintentional, an intentional outage would be e.g., where maintenance istaking place) or when the power supplies are configured to deliver powerto alternative building systems. In various embodiments, the network maybe configured to utilize energy-well-only power delivery in the event ofa power outage, and to utilize power delivery from any available powersource (e.g., power supplies and/or energy wells) or combination ofpower sources in non-power-outage situations.

Power networks with energy wells allow the control panel(s) to have alower maximum power output than would otherwise be needed to drive allthe windows simultaneously if no such energy wells were provided.Returning to the embodiment of FIG. 5, because the control panel 510 canhave a relatively lower maximum power output, the control panel 510 maynot need as many safeguards as are needed for higher output panels.Further, the control panel may be less expensive than it otherwise wouldbe, if made to supply peak load output on its own.

Any type of local energy storage may be used for the energy wells.Examples include supercapacitors and batteries, which may be provided inthe form of uninterruptible power supplies (UPSs). Battery energy wellsmay take various forms, e.g., a rechargeable battery, storage battery,secondary cell, or accumulator, which can be charged, discharged into aload, and recharged many times. The term “accumulator” is used as itaccumulates and stores energy through a reversible electrochemicalreaction. Rechargeable batteries are produced in many different shapesand sizes, ranging from button cells to megawatt systems connected tostabilize an electrical distribution network. Examples of differentcombinations of electrode materials and electrolytes may be used,including lead acid, nickel cadmium, nickel metal hydride, lithium ion,nickel zinc, and lithium ion polymer. In certain embodiments, an energywell of the power network is replaceable, modular format, that can beeasily accessible for maintenance, if needed.

The energy wells may provide sufficient power to drive one or moreoptical transitions in one or more windows. In some cases, an energywell may provide sufficient power to drive an optical transition in asmany as about 1, 2, 3, 5, 7, 10, or 12 windows simultaneously. Theenergy well can discharge at a rate sufficient to drive opticaltransitions in the relevant window(s) in its domain. The energy well maybe capable of providing a particular voltage sufficient to drive opticaltransitions in the relevant window(s). In various cases the energy wellmay discharge at a voltage of about 24 V. The power provided to theenergy well may be DC power in many cases. In some embodiments theenergy well may include a voltage converter for increasing or decreasingthe voltage provided to the energy well. In other cases the energy welloutputs power at the same voltage at which it is received. In certaincases, the energy well may be rated as a class 1 or a class 2 device.

In certain embodiments, an energy well can be an inline system, i.e., amodular format battery pack that installs into a trunk line or dropcable of the network. For example, one form of trunk line component is atrunk line cable with, e.g., a dock station. Similarly, a drop line maybe provided with such a dock station. A rechargeable battery pack isconfigured to mate with the dock station. A supercapacitor energy wellmay also be provided in such a format, though dock stations areparticularly beneficial in the case of battery packs because batteriestend to degrade over time and are more likely to need replacementcompared to supercapacitors. The battery pack (or other energy storageused for the energy well) and/or docking station may have electroniccircuitry for directing power to and from the battery pack into and outof the trunk line (or, if the docking station is provided in a dropline, for directing power into and out of the drop line) to feed thepower network. The electrical circuitry may include control logic fordeciding when and how much power to deliver to the network, and forexample may receive instructions from a network and/or a mastercontroller. Additionally, the electrical circuitry may include chargingcircuits that modulate how the battery pack (or other energy storageused for the energy well) is recharged, e.g., having a fast charge modeand a trickle charge mode. The circuitry may also include upgradecapability, e.g., built into the circuitry so that newer batterytechnology (or other energy storage technology) may be used in thefuture, or e.g., the circuitry itself may be a modular unit that can bereplaced when upgrades to it and/or the battery pack (or other energystorage) are desired. Thus in this respect, a power network as describedherein may be upgradeable, e.g., to increase total power output, bychanging the energy wells and/or associated circuitry, whether modularor not, without changing other components such as control panels, dropcables or other hardware. In one embodiment, a power network is upgradedto a higher peak output power simply by changing out one or more energywells (which may be battery packs, supercapacitors, or other energystorage mechanisms). This adds a great deal of flexibility in systems,e.g. when more windows are added to a network, batteries may be upgradedwithout having to change anything else in the system.

The National Electrical Code (NEC) is a regionally adoptable standardproviding guidelines for safe installation of electrical wiring andequipment in the US. The code is published by the National FireProtection Association (NFPA), which is a private trade association.Although the code is not national law, it has been adopted by manystates and municipalities, sometimes with amendments. The NEC definesvarious circuit classifications and provides limitations on thespecifications of such circuits. Broadly, the NEC defines class 1, class2, and class 3 circuits. The NEC further defines subcategories withinthese classes. For example, within the class 1 circuits, the NECdistinguishes between power-limited circuits (which are limited to 30 V,1000 V·A, and include a current limiter on the power source) andremote-control and signaling circuits (which are limited to 600 V andinclude limitations on the power output of the source). For class 1power-limited circuits, an overcurrent protection device (OCPD)restricts the amount of supply current on the circuit to protect thecircuit in the case of an overload, short circuit, or ground-fault. Theuse of class 1 components may involve special considerations withrespect to safety. For example, cabling provided in a class 1 circuitmay need to be specially rated class 1 cable, or it may need to be runin an appropriate conduit or metal raceway.

With respect to class 2 circuits, the NEC imposes limits based onwhether the circuit is inherently limited (requiring no overcurrentprotection) or not inherently limited (requiring a combination of powersource and overcurrent protection). In a number of cases, class 2circuits may be limited to 30 V and 100 V·A. Wiring in a class 2 circuitis inherently safer than in a class 1 circuit, and fewer precautions areneeded. For instance, cabling that is rated class 2 can be providedwithout the protections inherent to class 1 wiring, and does not need tobe provided in a conduit/raceway.

The energy wells described herein, as well as other components such ascontrol panels/power supplies and cabling, may be designed to satisfythe conditions listed in the NEC with respect to class 1 or class 2power supplies/circuits, depending on the particular installation needs.

One example of an energy well that may be used as described herein is asupercapacitor. In certain embodiments, a supercapacitor used as anenergy well has sufficient energy and power to drive a single opticaltransition (e.g., tinted to clear or vice versa) on an associatedelectrochromic window. The energy well may be integrated into theassociated electrochromic window, for example as a part of an individualwindow controller. In some other cases, the energy well may be separatefrom the windows and window controllers, positioned at some point (ormultiple points) along the power distribution network at a locationwhere it can be used to provide power to one or more windows on thenetwork. As mentioned above, in certain embodiments the energy well(s)may be installed along a trunk line, or on drop lines that connect thewindow controllers to the trunk line. Supercapacitors may be deployedfor discharge in scenarios where high power but relatively low capacityis needed such as driving a complete transition in a largeelectrochromic window, e.g., an electrochromic window having a dimensionof at least about 50 inches. In some cases, batteries andsupercapacitors are used together to complement one another. Batteriesoften store more energy than comparably sized supercapacitors, butdeliver such energy at lower power than comparably sizedsupercapacitors. In various embodiments, the supercapacitor may berecharged over the course of about 4 minutes, or over the course ofabout 2 minutes, or in about 1 minute or less.

The recharging may be controlled to balance the needs of the system. Forinstance, if the network is currently using a lot of the available powerto drive optical transitions in the windows, an energy well may remainuncharged until a time when there is sufficient excess power availableto recharge the energy wells. Further, if the amount of available poweris relatively low, the energy wells may be recharged at a relativelylower rate or in increments. Various energy wells may be chargedsimultaneously if sufficient power is available. In some cases, theenergy wells may be recharged at different starting times if there isnot sufficient power to simultaneously recharge all of the energy wells.In other words, the speed and timing of recharging may be controlled topromote optimal functionality of the electrochromic windows. In thisway, a user can operate the windows as desired on demand, and the energywells can be recharged at times that will not overtax the system.

One embodiment is an electrochromic window control system includingalgorithms and logic configured to recharge one or more energy wells ina power network. In one embodiment, the control system is configured tosimultaneously charge one energy well in a first charging format, whilecharging a second energy well in a second charging format, differentfrom the first charging format. For example, the first energy well is asuper capacitor and the second energy well is a battery. Each will becharged in a different format due to their inherent differences incapacity, structure, and so on. In another example, both the first andthe second energy wells are batteries, e.g., of the same type; however,one requires more charging than the other. The window control system cancharge each of the first and second energy wells as needed, e.g., thefirst energy well may only need a trickle charge because it will not beneeded for some time, based on scheduling, while the second energy wellmay need fast charging due to imminent window switching requirements.Just as the system may deliver power from power supplies to the energywells at differential rates and formats, so can the system deliver powerfrom the energy wells, at differential rates and formats, depending uponthe demands put upon the power network. Thus, embodiments describedherein provide much greater flexibility than conventional power networksfor electrochromic windows.

The number of energy wells used in a particular network may depend on anumber of factors including, for example, the maximum power provided bythe control panel, the number of windows per control panel, how quicklythe optical transitions are driven, the length of wiring connecting thecontrol panel to the windows, the number of wires used to connect to allthe windows, the energy capacity and power capacity of the energy wells,etc. Generally, the more energy that can be stored in and supplied bythe energy wells, the less power output is needed from the controlpanel(s). However, the control panel(s) should have an output capacitysufficient to recharge the energy wells.

In some implementations, an energy well is provided for eachelectrochromic window on the network, or for substantially eachelectrochromic window on the network (e.g., at least about 95% of theelectrochromic windows on the network). Such energy wells may beimplemented as part of an electrochromic window. In other words, theenergy well may be integrated into the window, for example integratedinto an IGU. In some embodiments, an energy well may be included in awindow controller, which may or may not be integrated into the window.In another implementation, a single energy well may supply power for agroup of windows. For instance, at least one energy well may be providedfor each n windows on the network, where n is between about 2 and about100, or where n is between about 5 and about 50, or where n is betweenabout 10 and about 30.

As mentioned, the use of energy wells can allow for a network to bedesigned using control panels/power supplies that operate at relativelylower power/voltage than would otherwise be needed to support theelectrochromic windows at their peak power requirements. This may reducethe cost of electrochromic window networks, since the controlpanels/power supplies can be class 2 devices that do not require theelectrical safeguards that are mandatory for non-class 2 power supplies(e.g., class 1 power supplies) providing higher power/voltage.

In certain embodiments, the control panel(s) in a power distributionnetwork may all be class 2 devices. In some cases, one or more controlpanel(s) in a power distribution network may be a class 1 device.Various details related to class 1 and class 2 specifications areprovided above and in the National Electric Code (NEC).

The use of energy wells helps manage the supply of power available todrive optical transitions on electrochromic windows on a network.Another technique for power management, which may be used in combinationwith the other techniques described herein, is to manage the demand forpower as described further below.

Managing Demand for Available Power

Where electrochromic windows are provided on a network, power can beconsumed by the windows, and sometimes their controllers, in a way thatensures that the windows will not draw a greater amount of power than isavailable. In some embodiments, the window power distribution networkincludes a normal demand procedure and a controlled demand procedure,with the latter reserved for situations that might otherwise requirepeak consumption and/or situations where the power supply is temporarilylimited (e.g., when the local utility cannot keep up with demand or whenthere is a malfunction).

One or more controllers (e.g., master controllers, network controllers,and/or window controllers) may take various actions as described hereinto manage demand for available power to ensure this result. Managingdemand for available power relates to managing the amount of power thatis drawn by the electrochromic windows and/or controllers on thenetwork. There are a number of reasons that it may be beneficial tomanage this demand. For instance, if the building experiences a powerfailure and the network only has a limited amount of power to work with(e.g., power stored in energy wells, power provided by a generator,etc.), a controller may take action to ensure that the windows do notdraw a greater amount of power than is available. Further, the networkmay be designed such that the peak power delivered to the windows isless than the power required to simultaneously drive optical transitionsin all the windows under normal transition parameters. In this case, acontroller may take action to ensure that the windows do not draw toomuch power at a given time, for example by slowing the transitions andoperating at lower power for each window, or by staggering or otherwiseprioritizing the optical transitions such that the windows are not eachdrawing large amounts of power at the same time. Implementation of asleep mode for the electrochromic windows and controllers may also helpmanage the demand for power on the network.

As explained, an optical transition of an electrochromic device may becontrolled by a window controller. The window controller may receiveinstructions from a network controller. The controllers may beconfigured to apply a particular current profile and/or voltage profilewhen driving an optical transition on an electrochromic device. Currentand/or voltage applied to the device can be controlled during variousportions of the transition.

FIG. 6 illustrates a voltage control profile in accordance with certainembodiments. In the depicted embodiment, a voltage control profile isemployed to drive the transition from a clear state to a tinted state(or to an intermediate state). To drive an electrochromic device in thereverse direction, from a tinted state to a clear state (or from a moretinted to less tinted state), a similar but inverted profile may beused. In some embodiments, the voltage control profile for going fromtinted to clear is a mirror image of the one depicted in FIG. 6.

The voltage values depicted in FIG. 6 represent the applied voltage(V_(app)) values. The applied voltage refers to the difference inpotential applied to two bus bars of opposite polarity on theelectrochromic device. The applied voltage profile is shown by thedashed line. For contrast, the current profile in the device is shown bythe solid line. In the depicted applied voltage profile, V_(app)includes four components: a ramp to drive component 603, which initiatesthe transition, a V_(drive) component 613, which continues to drive thetransition, a ramp to hold component 615, and a V_(hold) component 617.The ramp components are implemented as variations in V_(app) and theV_(drive) and V_(hold) components provide constant or substantiallyconstant V_(app) magnitudes.

The ramp to drive component is characterized by a voltage ramp rate(increasing magnitude) and a magnitude of V_(drive). When the magnitudeof the applied voltage reaches V_(drive), the ramp to drive component iscompleted. The V_(drive) component is characterized by the value ofV_(drive) as well as the duration of V_(drive). The magnitude ofV_(drive) may be chosen to maintain V_(eff) within a safe but effectiverange over the entire face of the electrochromic device. Veff refers tothe “effective voltage,” which is the potential between the positive andnegative transparent conductive layers at any particular location on theoptically switchable device. In Cartesian space, the effective voltageis defined for a particular x,y coordinate on the device. At the pointwhere V_(eff) is measured, the two transparent conducting layers areseparated in the z-direction (by the device materials), but share thesame x,y coordinate.

The ramp to hold component is characterized by a voltage ramp rate(decreasing magnitude) and the value of V_(hold) (or optionally thedifference between V_(drive) and V_(hold)). V_(app) drops according tothe ramp rate until the value of V_(hold) is reached. The V_(hold)component is characterized by the magnitude of V_(hold) and the durationof V_(hold). Actually, the duration of V_(hold) is typically governed bythe length of time that the device is held in the tinted state (orconversely in the clear state). Unlike the ramp to drive, V_(drive), andramp to hold components, the V_(hold) component has an arbitrary length,which is independent of the physics of the optical transition of thedevice.

Each type of electrochromic device will have its own characteristiccomponents of the voltage profile for driving the optical transition.For example, a relatively large device and/or one with a more resistiveconductive layer will require a higher value of V_(drive) and possibly ahigher ramp rate in the ramp to drive component. U.S. patent applicationSer. No. 13/449,251, filed Apr. 17, 2012, and incorporated herein byreference, discloses controllers and associated algorithms for drivingoptical transitions over a wide range of conditions. As explainedtherein, each of the components of an applied voltage profile (ramp todrive, V_(drive), ramp to hold, and V_(hold), herein) may beindependently controlled to address real-time conditions such as currenttemperature, current level of transmissivity, etc.

The voltage and current profiles shown in FIG. 6 are examples, and manyother profiles may be used. In one example, open circuit conditions maybe periodically applied to help monitor how far along an opticaltransition has progressed. Additional information related to driving andmonitoring an optical transition is provided in PCT Patent ApplicationNo. PCT/US14/43514, filed Jun. 20, 2014, and titled, “CONTROLLINGTRANSITIONS IN OPTICALLY SWITCHABLE DEVICES,” which is hereinincorporated by reference in its entirety.

In some embodiments herein, one or more components of an applied voltageprofile (and/or current profile) may be controlled to manage the demandfor power on a network of electrochromic windows. This technique may beparticularly useful in cases where there is a power disruption or arelated need to conserve power. This technique may also be useful ineveryday operation, particularly where the network is not designed tosupport simultaneous full speed/full power optical transitions for allthe electrochromic windows. As noted above in the section related tomanaging the supply of available power, there are a number of reasonswhy a system might be designed in this manner.

In order to transition a window using relatively less power, a number ofoptions are available. For instance, the ramp to drive component and/orthe ramp to hold component may be set relatively less steep, and/or thedrive voltage may be set at a relatively lower magnitude value (closerto 0). These changes may increase the time period over which thetransition occurs.

With reference to FIG. 3, in one example a network 300 having a controlpanel 310 includes windows 301-306. Each window 301-306 can undergo anoptical transition over a duration of about 15 minutes under conditionswhere only some of the windows switch simultaneously. However, in thisexample, the control panel 310 cannot provide sufficient power tosimultaneously power optical transitions in all of the windows 301-306without experiencing a power failure (e.g., tripping the circuit). Ifand when a command is received to simultaneously switch the opticalstate of all the windows 301-306, one or more controllers on the networkmay direct the windows to switch optical states using an alternative setof transition parameters.

For instance, a controller may direct one or more of the windows totransition using a lower ramp to drive rate, a lower drive voltage,and/or a lower ramp to hold rate. This alteration in the transitionparameters may allow all of the windows to transition simultaneously,though at a slightly slower rate. For example, whereas the individualwindows could switch in about 15 minutes when driven at a first set oftransition parameters, the windows may switch over a longer period, forexample about 20 minutes, using a second set of transition parameterswhen all the windows are directed to switch simultaneously. Differentsets of transition parameters can be defined for various powerconditions. The power conditions may relate to the amount of power thatis available to be supplied on the network compared to the amount ofpower that is in demand on the network.

In some cases, the first set of transition parameters may relate to adefault set of transition parameters that are used when the supply ofavailable power on the network is greater than the demand for power onthe network. This first set of transition parameters may be optimized toprovide fast switching or another desirable characteristic. A second setof transition parameters may relate to another set of parameters thatmay be used when the supply of available power on the network is lessthan the demand for power on the network. In this case, the second setof transition parameters may be optimized to conserve power, forinstance by transitioning the windows at a slower rate and effectivelylowering the demand for power. Any number of sets of parameters can bedefined for various particular power conditions.

In certain embodiments, there may be particular quantitative differencesbetween the transition parameters used for a default mode and those usedfor a power conservation mode. For example, the magnitude of the maximumramp rate (V/s) experienced during a ramp to drive portion of atransition (e.g., see 603 in FIG. 6) under the default mode may be atleast a certain degree greater than the magnitude of the maximum ramprate experienced during a ramp to drive portion of a similar transitionunder the power conservation mode. The magnitude of the ramp rate duringthe ramp to drive portion of the transition may be at least about 5%higher (e.g., 10% higher, 20% higher, 30% higher, 40% higher, or 50%higher) for the default mode than for the power conservation mode.Similarly, the magnitude of the drive voltage (V_(drive)) during thedrive component of a transition (e.g., see 613 in FIG. 6) under thedefault mode may be at least a certain degree higher than the magnitudeof the drive voltage during the drive component of the transition underthe power conservation mode. The magnitude of the drive voltage may beat least about 5% higher (e.g., 10% higher, 20% higher, 30% higher, 40%higher, or 50% higher) for the default mode than for the powerconservation mode. The magnitude of the ramp rate during a ramp to holdportion of the transition (e.g., see 615 in FIG. 6) may be at least acertain degree greater or less in the case of the default mode comparedto the power conservation mode, which may be a difference of at leastabout 5% (e.g., at least about 10%, 20%, 30%, 40%, or 50%). Asexplained, the power conservation mode may result in a slower transitioncompared to the default mode. In some cases, the duration of an opticaltransition may be at least about 5% longer (e.g., 10% longer, 20%longer, 50% longer, 75% longer, or 100% longer) under the powerconservation mode compared to the default mode.

Another technique for managing the demand for power on a network ofelectrochromic windows relates to prioritization of transitions overmultiple windows. For instance, if a command is received to drive anoptical transition in many windows simultaneously and there is notsufficient available power to do so, a controller (e.g., a networkcontroller or other controller) may direct certain windows to begintransitioning before others do. These other windows may then be directedto begin changing when there is sufficient power available to drive thetransitions. In this way, the controller can ensure that the power beingdemanded by and delivered to the windows remains within the range ofpower that is able to be supplied by the network. The transitions forthe different windows may be overlapping or non-overlapping in time. Thewindows may be directed to start transitioning individually (on awindow-by-window basis) or in groups.

With reference to FIG. 3, in one example the control panel 310 iscapable of simultaneously powering optical transitions in threeelectrochromic windows. Where a command is received to drive atransition in all of the windows, a controller may direct windows301-303 to change first, and then windows 304-306 to change second. Inanother example, a controller may direct the windows to change in a morecontinuous manner, for example directing additional windows to beginchanging as soon as there is sufficient power available to do so, evenif other transitions are still ongoing.

The controllers may be configured to prioritize the transitions in aparticular way, for example favoring certain windows over others, e.g.,differentiating by window and/or by zone of windows. In one example, acontroller receiving a command to transition all of the windows mayexecute the command such that windows on a particular side of thebuilding change first. This may be useful where one side of the buildingis experiencing strong incident light and it is more important thatwindows on this side of the building tint quickly. The windows can begrouped (e.g., to define multiple zones) and prioritized as desired fora particular application. Prioritization is further described in PCTPatent Application No. PCT/US15/38667, filed Jun. 30, 2015, and titled“CONTROL METHODS AND SYSTEMS FOR NETWORKS OF OPTICALLY SWITCHABLEWINDOWS DURING REDUCED POWER AVAILABILITY,” which is herein incorporatedby reference in its entirety.

Another technique that can be used to manage the amount of availablepower is to implement electrochromic windows that may be set to a sleepmode. In some conventional electrochromic window networks, each windowcontroller consumes about 1-2 Watts even when it is not activelycontrolling a window. Each window may be provided with its owncontroller, and this wasted power can add up. By enabling a windowcontroller to enter sleep mode, this power can be conserved. In oneexample a controller in sleep mode may periodically power on to “wakeup” and check whether it has received any commands. If such commandshave been received, the controller may execute them upon waking up. Ifno such commands have been received, the controller may go back intosleep mode. When asleep, the controller may draw essentially no power.

In various embodiments, a network of electrochromic windows may includeparticular sensors that are used to sense the level of voltage and/orcurrent passing to/from/through various components of the network. Forexample, sensors may be used to determine the voltage and/or current (a)delivered from a window controller to an electrochromic window, (b)delivered to a window controller, (c) delivered to or from a powersource, control panel, energy well, etc. Such sensors may be useful inidentifying problematic situations within the network, for example toidentify where and when a component therein is failing or has failed.

The embodiments disclosed herein provide significant flexibility indesigning, operating, maintaining, and upgrading networks ofelectrochromic windows. By managing the supply and/or demand foravailable power, the network can be configured in a way that avoids“over-engineering” the power distribution network. An over-engineeredpower distribution network may be one that uses more cabling, higherrated cabling and related protections (e.g., class 1 as opposed to class2), higher rated power supplies or other power delivery components(e.g., class 1 as opposed to class 2), etc. As discussed above,conventional power distribution networks tend to be over-engineered inorder to accommodate the peak power that must be collectively deliveredto the electrochromic windows. By managing the supply and/or demand forpower as discussed herein, the peak power can be more easilyaccommodated without over-engineering the power delivery network.

Responses in the Case of a Power Emergency

A number of the techniques described herein, including both those usedfor managing supply of available power and for managing demand ofavailable power, may be used to address situations that arise due topower emergencies. Example power emergencies include, but are notlimited to, blackouts, brownouts, rolling blackouts and brownouts,severe weather affecting power delivery, and emergency responsesituations to particular threats (fire, criminal activity, etc.), andany other event that results in limited power delivery to a building. Inthese situations, various components on a power distribution network mayadapt in particular ways and/or take particular actions to avoiddamaging components on the network.

In some cases where a power emergency occurs, one or more components onthe network may be configured to cause the individual electrochromicwindows to transition to a safe state before the supply of availablepower is completely exhausted. For example, when power to a building iscut off or limited, one or more controllers on the network may beconfigured to draw power from energy wells or other local energy storageunits on the power distribution network. The controller(s) may befurther configured to cause the power to be delivered to the windows ina manner that transitions the windows to a state in which they will notbe damaged if/when the power is exhausted. In many cases, the windowwill be completely or substantially clear when it is in its safe state.This scenario provides one reason that it is beneficial in certain casesto design a power distribution network to include local energy storageunits that collectively have sufficient capacity to power at least onetransition to a safe state for all windows on the network.

Another technique that can be utilized when there is a power emergencyrelates to the power used by individual controllers on the network. Asnoted herein, controllers consume some amount of power, even when theyare not actively controlling a window transition. The controllers may beconfigured to turn off or go into a sleep mode in response to a poweremergency. The controller may be put into sleep mode or powered offafter transitioning the window to a safe state in some cases.

An additional technique that can help address a power emergency relatesto prioritizing transitions on certain windows over others. As describedabove, prioritization can be used to stagger transitions of individualwindows according to the needs of a particular building/situation. Incertain implementations, windows that are relatively more expensive(e.g., larger windows, oddly-shaped windows, custom-built windows, etc.)may be prioritized to transition to a safe state before less expensivewindows. This may help limit any damage that is experienced to lessexpensive windows. The prioritization used may depend on thecharacteristics of the windows being transitioned. For example, in someimplementations, the windows may be prioritized such that small windowstransition to a safe state before large windows. This prioritizationscheme may be useful in cases where the power used to transition onelarge window could be used to power transitions on multiple smallwindows, where the cost to fix the multiple small windows would begreater than the cost to fix the one large window.

Another technique to address power emergencies relates to altering thetransition parameters on the windows being transitioned. By altering thetransition parameters, the overall power used to transition the windowsmay be minimized, and the number of windows that can transition to asafe state may be maximized. Each of these power management techniquesis described further herein.

In certain implementations, the power distribution network may transferstored energy (e.g., from one or more energy wells) to other buildingsystems in the case of an emergency. Such other systems may include,e.g., emergency lighting systems, security systems (e.g., locks, alarms,etc.), a public address (PA) system, a sprinkler or other firesuppression system, etc. The energy wells may collectively storesufficient energy to simultaneously transition all of the windows on thenetwork, as well as any energy needed to be transferred to the otherbuilding systems to ensure safety/security.

Wiring Considerations

The configuration used to wire the various windows together in a networkcan affect how efficiently power is transferred over the network. Thenumber of electrochromic devices that can be supported on a power cableis limited by factors including the length and gauge of wiring that isused, the power used by each window, the voltage drop occurring at eachwindow, etc. It is generally beneficial to use less wiring, so long asthe wiring provides sufficient power to drive the windows as desired.Wiring used to transfer power may also be used to transfer communicationsignals.

FIGS. 7 and 8 present schematic views of wiring configurations that maybe used in certain embodiments. The networks shown in FIGS. 7 and 8 arepower distribution networks that may also serve as communicationnetworks. In FIG. 7, a class 1 control panel is used with class 1 trunklines rated at 8 Amps each. Power delivery in this embodiment issegmented, with four separate power delivery lines connecting thecontrol panel to different points along the trunk lines. The wiresbetween the trunk line and the window controllers are called “droplines.” Wires that provide power from a power supply to a trunk line maybe referred to as power injector lines or power insert lines. Inembodiments where the power distribution network includes energy wells,a cable connecting an energy well with the trunk line (or with a dropline) may also be referred to as power injector line or power insertline (though it is understood that the energy wells may also be providedinline on, e.g., a trunk line and/or drop line). In the embodiment ofFIG. 7, each of the power injector lines is rated at 15 Amps and 600 V.In some cases the power injector lines may be power limited tray cables(PLTC), as shown in FIG. 7. Each power injector line in this exampleprovides power for up to about 32 window controllers (WCs) and theirrelated windows. For the sake of clarity only two window controllers areshown for each power injector line. Each window controller may beconnected to (or integral with) an electrochromic window, though for thesake of clarity only a single electrochromic window is shown in each ofFIGS. 7 and 8. A separate communication line may be provided, as shownin FIG. 7, to transfer communication/control information between thecontrol panel and the trunk line, where it can be delivered to theindividual window controllers. The trunk line may carry both power andcommunication information. Alternatively, communication information maybe transferred wirelessly, or the trunk line may be directly connectedto the control panel.

In FIG. 8, a class 2 control panel is used in combination with class 2trunk lines and class 2 power injector lines. The trunk lines in thiscase connect directly to the control panel. The class 2 trunk line andclass 2 power injector lines may be rated at less than about 4 Amps. Theuse of a class 2 control panel/wiring may limit the number of windowsthat can be driven by individual power lines connected to the class 2control panel. In this embodiment, up to about 16 window controllers maybe powered by each power injector line (for the sake of clarity only onewindow controller is shown per power injector line). In FIG. 8, transferof communication information may occur over the trunk line itself orthrough wireless communication.

The power distribution networks shown in FIGS. 7 and 8 may be modifiedto include additional energy storage units, for example the energy wellsdescribed herein. Such energy wells may increase the number ofelectrochromic windows/window controllers that may be powered by eachpower line. As noted above, the energy wells may be attached to orinline with the trunk lines, drop lines, power injector lines, or somecombination thereof.

FIGS. 9-11 present simplified top-down views of a network ofelectrochromic windows installed on one floor of a building. For thesake of simplicity, only two electrochromic windows are shown on eachface of the building, though it should be understood that manyadditional electrochromic windows may be present on the network. In FIG.9, the control panel 920 is connected to two trunk lines 921 and 922.One trunk line 921 provides power to windows 901-904 and the other trunkline 922 provides power to windows 905-908. Power is provided to eachwindow via a window controller (not shown) that may be connected to orintegral with each window. In this implementation, the maximum powerthat may be delivered to the windows/window controllers is limited bythe power output of the control panel 920.

In the embodiment of FIG. 10, two control panels 1020 and 1025 areprovided. Each control panel has two trunk lines connected thereto.Control panel 1020 is connected to trunk lines 1021 and 1022, whilecontrol panel 1025 is connected to trunk lines 1026 and 1027. Each trunkline in this figure is shown as controlling two windows 1001-1008(though many more may be provided). The control panels are positionednear the north and south faces of the building. In another embodiment,the control panels may be positioned near the east and west faces of thebuilding. It may be beneficial to use more than one control panel, forexample where a large number of electrochromic windows are present,where the building is large and/or the wiring is long, where manywindows often transition simultaneously, etc.

In certain implementations, control panels may be strategically locatedto provide power as needed to multiple windows. For example, if it isknown that windows on a particular side of a building are likely toswitch simultaneously, it may be beneficial to ensure that sufficientpower will be available to switch all of the relevant windows at once.One technique to accomplish this is to ensure that the windows on thisside of the building are driven by multiple control panels. In thecontext of FIG. 10, for example, it may be that all the windows on theeast-facing side of the building will all transition to a tinted statearound sunrise. In this example the east-facing windows are 1006 and1007, though in many embodiments a particular side of a building willinclude a much higher number of electrochromic windows, thereby makingpower distribution from multiple control panels more attractive. Becausewindows 1006 and 1007 are driven by separate control panels 1020 and1025, respectively, there is a lower risk that the power needed tosimultaneously drive the windows 1006 and 1007 will exceed the availablepower. Such power management issues become more important when thenumber of electrochromic windows is higher, though only a few windowsare shown in the figure for the sake of simplicity. In some similarembodiments, each control panel may provide power to windows on multiplefloors.

Similar considerations may come into play when considering whether andwhere to connect power injection lines. For instance, instead ofensuring that windows on a particular side of the building are suppliedpower from different control panels, the network may be designed suchthat windows on a particular side of the building are supplied powerfrom different power injection lines. In this way, the power deliveredto the windows on that side of a building (which as described above maybe controlled to undergo a simultaneous optical transition) may belimited by the power output of the control panel, but is not limited bythe amount of power/voltage that can be carried over a single powerdelivery line. This technique helps avoid wiring limitations that arisedue to line loss, for example. The techniques related to the use ofmultiple control panels and the use of multiple power injection lines todeliver power to windows likely to transition simultaneously can becombined as appropriate for a desired application.

In the embodiment of FIG. 11, a single control panel 1120 is used. Thecontrol panel 1120 is connected to two trunk lines 1121 and 1122. Trunkline 1121 provides power to windows 1101-1104, while trunk line 1122provides power to windows 1105-1108. In this embodiment, two energywells 1130 and 1131 (EWs) are provided on the power lines 1121 and 1122,respectively. The energy wells 1130 and 1131 may provide a boost ofpower to transition the various windows as needed. For example, if acommand is received to simultaneously transition windows 1101-1104 andthe power used by windows 1101-1104 to transition exceeds the power thatcan be delivered by the control panel 1120 over power line 1121, theenergy well 1130 may make up the deficit by discharging to powertransitions on window 1103 and/or 1104. The energy well 1130 canrecharge itself after the transitions are complete, or even before thetransitions are complete if/when the relevant windows are collectivelyusing less power than can be provided by the control panel 1120 overpower line 1121. Of course, the techniques described above related toprioritization and/or adaptation of transition parameters may also beused to avoid drawing too much power.

System Flexibility and Upgrades

One advantage of the disclosed techniques is that it enableselectrochromic window networks to be more flexible over time. Forexample, in many conventional networks of electrochromic windows, thesystem will be sized/designed/implemented a single time. The powerrequirements of the various components (e.g., control panels) aredetermined based in part on the number of windows to be included on thenetwork. If installation of additional electrochromic windows onto thenetwork is desired, it can be very challenging. For example, theinclusion of additional windows may render the network incapable ofproviding sufficient power to drive all (or many) of the windows atonce. However, where the power supply and power demand managementtechniques disclosed herein are used, the network is much more capableof expanding to include additional electrochromic windows. Additionalenergy wells may be provided as additional windows are installed tostore energy that may be needed to drive the additional windows.Further, the logic used to distribute power throughout the network maytake into account the increased demand related to the additionalwindows, and either adjust the transition parameters and/or prioritizethe window transitions as needed.

One embodiment may relate to a method of modifying a network ofelectrochromic windows to include one or more additional electrochromicwindows. The network may have a power supply that would be incapable ofsupporting simultaneous optical transitions on all of the electrochromicwindows (including the additional windows) using the transitionparameters typically used to drive the transitions before inclusion ofthe additional windows. By using one or more of the techniques describedherein, the modified network may be able to support simultaneoustransitions on all of the windows, even without performing a majorredesign of the network and power supply.

System Notifications

One advantage of the disclosed embodiments is that a network ofelectrochromic windows can operate in a “diminished performance” stateinstead of completely failing. In many conventional networks, thewindows will generally perform at optimum conditions until there is anissue and the entire network fails. For instance, a network of windowsmay operate perfectly until the demand for power exceeds the availablesupply of power, at which point the circuit may trip and the entirenetwork may fail. This failure can end up damaging the electrochromicdevices in some cases. By contrast, with a number of the disclosedtechniques, a network may be able to keep the windows running and avoida power failure in cases where the demand for power approaches orexceeds the power being input into the network. For instance, the use ofenergy wells may increase the supply of power beyond that which issupplied to the network by the control panel/power supply. Further,adjustment of transition parameters and/or prioritization of transitionscan help manage/lower demand for power to ensure that it remains belowwhat is able to be supplied. While the windows may operate at a slowertransition rate, or in a staggered pattern, this operational state ofdiminished performance is far preferable to a non-operational state andthe related risk of electrochromic device damage. Such performancedifferences may not even be noticeable to users in many cases.

In certain embodiments, a system may notify a user/administrator/etc.when the network is experiencing some type of problem. The problem maybe identified in some cases by a comparison of power being demanded vs.power being supplied, or by a difference in operation compared to normaloperating conditions. Where the network detects that a problem hasoccurred (e.g., a window has shorted out, a power supply has failed,windows are transitioning slower or in a staggered manner, a wire hasbecome pinched, etc.), a notification may be sent to auser/administrator/etc. to let them know there is a problem. In thisway, problematic components or issues within the network can beidentified and addressed before there is a system wide failure. Forinstance, if one window begins to fail and starts using more power thanit should, the network may recognize this problem and adjust thetransition parameters and/or prioritization of windows to ensure thatthe windows on the network do not attempt to draw more power than can besupplied by the network. The system can send a notification to abuilding administrator to let them know that there is a problem with theparticular window. The administrator can then take action to have thewindow fixed, possibly even before it stops working. In this way,serious disruptions to the system can be minimized or avoided. Many ofthe building occupants may never even realize there was a problem.Compared to conventional systems where similar failures may result infailure of the entire network, the disclosed embodiments representsubstantial improvements.

Controllers

FIG. 12 depicts a window controller 1214, which may be deployed as, forexample, component 1250. In some embodiments, window controller 1214communicates with a network controller over a communication bus 1262.For example, communication bus 1262 can be designed according to theController Area Network (CAN) vehicle bus standard. In such embodiments,first electrical input 1252 can be connected to a first power line 1264while second electrical input 1254 can be connected to a second powerline 1266. In some embodiments, as described above, the power signalssent over power lines 1264 and 1266 are complementary; that is,collectively they represent a differential signal (e.g., a differentialvoltage signal). In some embodiments, line 1268 is coupled to a systemor building ground (e.g., an Earth Ground). In such embodiments,communication over CAN bus 1262 (e.g., between microcontroller 1274 andnetwork controller 1212) may proceed along first and secondcommunication lines 1270 and 1272 transmitted through electricalinputs/outputs 1258 and 1260, respectively, according to the CANopencommunication protocol or other suitable open, proprietary, or overlyingcommunication protocol. In some embodiments, the communication signalssent over communication lines 1270 and 1272 are complementary; that is,collectively they represent a differential signal (e.g., a differentialvoltage signal).

In some embodiments, component 1250 couples CAN communication bus 1262into window controller 1214, and in particular embodiments, intomicrocontroller 1274. In some such embodiments, microcontroller 1274 isalso configured to implement the CANopen communication protocol.Microcontroller 1274 is also designed or configured (e.g., programmed)to implement one or more drive control algorithms in conjunction withpulse-width modulated amplifier or pulse-width modulator (PWM) 1276,smart logic 1278, and signal conditioner 1280. In some embodiments,microcontroller 1274 is configured to generate a command signalV_(COMMAND), e.g., in the form of a voltage signal, that is thentransmitted to PWM 1276. PWM 1276, in turn, generates a pulse-widthmodulated power signal, including first (e.g., positive) componentV_(PW1) and second (e.g., negative) component V_(PW2), based onV_(COMMAND). Power signals V_(PW1) and V_(PW2) are then transmittedover, for example, interface 1288, to IGU 1202, or more particularly, tobus bars in order to cause the desired optical transitions in theelectrochromic device. In some embodiments, PWM 1276 is configured tomodify the duty cycle of the pulse-width modulated signals such that thedurations of the pulses in signals V_(PW1) and V_(PW2) are not equal:for example, PWM 1276 pulses V_(PW1) with a first 60% duty cycle andpulses V_(PW2) for a second 40% duty cycle. The duration of the firstduty cycle and the duration of the second duty cycle collectivelyrepresent the duration, T_(PWM) of each power cycle. In someembodiments, PWM 1276 can additionally or alternatively modify themagnitudes of the signal pulses V_(PW1) and V_(PW2).

In some embodiments, microcontroller 1274 is configured to generateV_(COMMAND) based on one or more factors or signals such as, forexample, any of the signals received over CAN bus 1262 as well asvoltage or current feedback signals, V_(FB) and I_(FB) respectively,generated by PWM 276. In some embodiments, microcontroller 1274determines current or voltage levels in the electrochromic device basedon feedback signals I_(FB) or V_(FB), respectively, and adjustsV_(COMMAND) according to one or more rules or algorithms to effect achange in the relative pulse durations (e.g., the relative durations ofthe first and second duty cycles) or amplitudes of power signals V_(PW1)and V_(PW2) to produce voltage profiles as described above. Additionallyor alternatively, microcontroller 1274 can also adjust V_(COMMAND) inresponse to signals received from smart logic 1278 or signal conditioner1280. For example, a conditioning signal V_(CON) can be generated bysignal conditioner 1280 in response to feedback from one or morenetworked or non-networked devices or sensors, such as, for example, anexterior photosensor or photodetector 1282, an interior photosensor orphotodetector 1284, a thermal or temperature sensor 1286, or a tintcommand signal V_(TC). For example, additional embodiments of signalconditioner 1280 and V_(CON) are also described in U.S. Pat. No.8,705,162, which is incorporated by reference herein.

In certain embodiments, V_(TC) can be an analog voltage signal between 0V and 10 V that can be used or adjusted by users (such as residents orworkers) to dynamically adjust the tint of an IGU 1202 (for example, auser can use a control in a room or zone of a building similarly to athermostat to finely adjust or modify a tint of the IGUs 1202 in theroom or zone) thereby introducing a dynamic user input into the logicwithin microcontroller 274 that determines V_(COMMAND). For example,when set in the 0 to 2.5 V range, V_(TC) can be used to cause atransition to a 5% T state, while when set in the 2.51 to 5 V range,V_(TC) can be used to cause a transition to a 20% T state, and similarlyfor other ranges such as 5.1 to 7.5 V and 7.51 to 10 V, among otherrange and voltage examples. In some embodiments, signal conditioner 1280receives the aforementioned signals or other signals over acommunication bus or interface 1290. In some embodiments, PWM 1276 alsogenerates V_(COMMAND) based on a signal V_(SMART) received from smartlogic 1278. In some embodiments, smart logic 1278 transmits V_(SMART)over a communication bus such as, for example, an Inter-IntegratedCircuit (I²C) multi-master serial single-ended computer bus. In someother embodiments, smart logic 1278 communicates with memory device 1292over a 1-WIRE device communications bus system protocol (by DallasSemiconductor Corp., of Dallas, Tex.).

In some embodiments, microcontroller 1274 includes a processor, chip,card, or board, or a combination of these, which includes logic forperforming one or more control functions. Power and communicationfunctions of microcontroller 1274 may be combined in a single chip, forexample, a programmable logic device (PLD) chip or field programmablegate array (FPGA), or similar logic. Such integrated circuits cancombine logic, control and power functions in a single programmablechip. In one embodiment, where one pane has two electrochromic devices(e.g., on opposite surfaces) or where IGU 1202 includes two or morepanes that each include an electrochromic device, the logic can beconfigured to control each of the two electrochromic devicesindependently from the other. However, in one embodiment, the functionof each of the two electrochromic devices is controlled in a synergisticfashion, for example, such that each device is controlled in order tocomplement the other. For example, the desired level of lighttransmission, thermal insulative effect, or other property can becontrolled via a combination of states for each of the individualelectrochromic devices. For example, one electrochromic device may beplaced in a colored state while the other is used for resistive heating,for example, via a transparent electrode of the device. In anotherexample, the optical states of the two electrochromic devices arecontrolled so that the combined transmissivity is a desired outcome.

In general, the logic used to control electrochromic device transitionscan be designed or configured in hardware and/or software. In otherwords, the instructions for controlling the drive circuitry may be hardcoded or provided as software. In may be said that the instructions areprovided by “programming.” Such programming is understood to includelogic of any form including hard coded logic in digital signalprocessors and other devices which have specific algorithms implementedas hardware. Programming is also understood to include software orfirmware instructions that may be executed on a general purposeprocessor. In some embodiments, instructions for controlling applicationof voltage to the bus bars are stored on a memory device associated withthe controller or are provided over a network. Examples of suitablememory devices include semiconductor memory, magnetic memory, opticalmemory, and the like. The computer program code for controlling theapplied voltage can be written in any conventional computer readableprogramming language such as assembly language, C, C++, Pascal, Fortran,and the like. Compiled object code or script is executed by theprocessor to perform the tasks identified in the program.

As described above, in some embodiments, microcontroller 1274, or windowcontroller 1214 generally, also can have wireless capabilities, such aswireless control and powering capabilities. For example, wirelesscontrol signals, such as radio-frequency (RF) signals or infra-red (IR)signals can be used, as well as wireless communication protocols such asWiFi (mentioned above), Bluetooth, Zigbee, EnOcean, among others, tosend instructions to the microcontroller 1274 and for microcontroller1274 to send data out to, for example, other window controllers, anetwork controller 1212, or directly to a BMS 1210. In variousembodiments, wireless communication can be used for at least one ofprogramming or operating the electrochromic device, collecting data orreceiving input from the electrochromic device or the IGU 1202generally, collecting data or receiving input from sensors, as well asusing the window controller 1214 as a relay point for other wirelesscommunications. Data collected from IGU 1202 also can include countdata, such as a number of times an electrochromic device has beenactivated (cycled), an efficiency of the electrochromic device overtime, among other useful data or performance metrics.

The window controller 1214 also can have wireless power capability. Forexample, window controller can have one or more wireless power receiversthat receive transmissions from one or more wireless power transmittersas well as one or more wireless power transmitters that transmit powertransmissions enabling window controller 1214 to receive powerwirelessly and to distribute power wirelessly to electrochromic device.Wireless power transmission includes, for example, induction, resonanceinduction, RF power transfer, microwave power transfer, and laser powertransfer. For example, U.S. Pat. No. 9,081,246, incorporated byreference herein, describes in detail various embodiments of wirelesspower capabilities.

In order to achieve a desired optical transition, the pulse-widthmodulated power signal is generated such that the positive componentV_(PW1) is supplied to, for example, a first bus bar during the firstportion of the power cycle, while the negative component V_(PW2) issupplied to, for example, a second bus bar during the second portion ofthe power cycle.

In some cases, depending on the frequency (or inversely the duration) ofthe pulse-width modulated signals, this can result in the first bus barfloating at substantially the fraction of the magnitude of V_(PW1) thatis given by the ratio of the duration of the first duty cycle to thetotal duration t_(PWM) of the power cycle. Similarly, this can result inthe second bus bar floating at substantially the fraction of themagnitude of V_(PW2) that is given by the ratio of the duration of thesecond duty cycle to the total duration t_(PWM) of the power cycle. Inthis way, in some embodiments, the difference between the magnitudes ofthe pulse-width modulated signal components V_(PW1) and V_(PW2) is twicethe effective DC voltage across terminals 1246 and 1248, andconsequently, across the electrochromic device. Said another way, insome embodiments, the difference between the fraction (determined by therelative duration of the first duty cycle) of V_(PW1) applied to thefirst bus bar and the fraction (determined by the relative duration ofthe second duty cycle) of V_(PW2) applied to the second bus bar is theeffective DC voltage V_(EFF) applied to electrochromic device. Thecurrent I_(EFF) through the load—electromagnetic device—is roughly equalto the effective voltage V_(EFF) divided by the effective resistance orimpedance of the load.

Controllers for controlling optical transitions on optically switchabledevices (and networks of such devices) are further described in U.S.Provisional Patent Application No. 62/248,181, filed Oct. 29, 2015, andtitled “CONTROLLERS FOR OPTICALLY-SWITCHABLE DEVICES,” which is hereinincorporated by reference in its entirety.

Those of ordinary skill in the art will also understand that thisdescription is applicable to various types of drive mechanism includingfixed voltage (fixed DC), fixed polarity (time varying DC) or areversing polarity (AC, MF, RF power etc. with a DC bias).

The controller may be configured to monitor voltage and/or current fromthe optically switchable device. In some embodiments, the controller isconfigured to calculate current by measuring voltage across a knownresistor in the driving circuit. Other modes of measuring or calculatingcurrent may be employed. These modes may be digital or analog.

1. A method of modifying a pre-existing network of electrochromicwindows, the method comprising: installing one or more additional windowassemblies in the pre-existing network of window assemblies, thepre-existing network comprising: two or more window assemblies, eachwindow assembly comprising at least one electrochromic panel; two ormore window controllers, each window controller electrically connectedto one of the window assemblies; and one or more power suppliescollectively having a maximum power output, wherein: before installationof the one or more additional window assemblies: a first amount of powerused to simultaneously drive optical transitions on all of the windowassemblies using a first set of drive transition parameters iscollectively below the maximum power output; and after installing theone or more additional window assemblies: a second amount of power usedto simultaneously drive optical transitions on all of the windowassemblies using the first set of drive transition parameterscollectively exceeds the maximum power output; and the network isconfigured to to simultaneously drive optical transitions on all of thewindow assemblies without demanding a level of power from the one ormore power supplies that exceeds the maximum power output.
 2. The methodof claim 1, further comprising installing one or more energy wells inelectrical communication with (a) the one or more power supplies and (b)the two or more window assemblies of the pre-existing network and/or theone or more additional window assemblies.
 3. The method of claim 1,wherein the method excludes installation of any additional powersources.
 4. The method of claim 3, wherein the pre-existing networkfurther comprises one or more energy wells in addition to the one ormore power supplies.
 5. The method of claim 1, wherein: beforeinstalling the one or more additional window assemblies, the network isconfigured to use the first set of drive transition parameters to driveoptical transitions on the window assemblies; and after installing theone or more additional window assemblies, the network is configured touse a modified set of drive transition parameters to drive opticaltransitions on the window assemblies, wherein the modified set of drivetransition parameters results in a lower power usage per windowassembly, per unit time, compared to the first set of drive transitionparameters.
 6. The method of claim 5, wherein each of the first set ofdrive transition parameters and the modified set of drive transitionparameters comprises a ramp to drive voltage rate, and wherein the rampto drive voltage rate of the modified set of drive transition parametershas a lower magnitude than the ramp to drive voltage rate of the firstset of drive transition parameters.
 7. The method of claim 5, whereineach of the first set of drive transition parameters and the modifiedset of drive transition parameters comprises a drive voltage, andwherein the drive voltage of the modified set of drive transitionparameters has a lower magnitude than the drive voltage of the first setof drive transition parameters.
 8. A network comprising: (a) two or morewindow assemblies, each including: at least one electrochromic pane, awindow controller for driving optical transitions on the electrochromicpane, and a supercapacitor for powering optical transitions on theelectrochromic pane; and (b) a power supply electrically connected withthe window assemblies, wherein the network is configured to transferpower from the supercapacitors to the electrochromic panes when thewindow assemblies collectively demand a greater amount of power than canbe provided by the power supply, and to transfer power from the powersupply to the supercapacitors to recharge the supercapacitors when thewindow assemblies collectively demand a lower amount of power than canbe provided by the power supply.
 9. The network of claim 8, furthercomprising; a network controller and/or master controllercommunicatively coupled with the window controller of each of the two ormore window assemblies; wherein the network controller and/or mastercontroller is configured to cause one or more of the window assembliesto undergo a first optical transition using a first set of transitionparameters when a first condition is present, and to cause one or moreof the window assemblies to undergo a second optical transition using asecond set of transition parameters when a second condition is present,the first condition being different from the second condition.
 10. Thenetwork of claim 9, wherein the first condition relates to a conditionwhere the window assemblies collectively demand relatively more power,and wherein the second condition relates to a condition where the windowassemblies collectively demand relatively less power.
 11. The network ofclaim 9, wherein the first condition relates to a condition where thewindow assemblies directed to transition would collectively demand, iftransitioned using the second set of transition parameters, either (i)more power than can be provided by the power supply, or (ii) more than acertain fraction of the power that can be provided by the power supply.12. A network comprising: (a) two or more window assemblies, eachcomprising: at least one electrochromic pane, and a window controllerfor driving optical transitions on the electrochromic pane; (b) a powersupply electrically connected with the window assemblies; and (c) one ormore energy wells electrically connected with the power supply and withthe window assemblies, wherein the network is configured to: (i)transfer power from the one or more energy wells to the windowassemblies when the window assemblies collectively demand a greateramount of power than can be provided by the power supply, (ii) transferpower from the power supply to the one or more energy wells to rechargethe one or more energy wells when the window assemblies collectivelydemand a lower amount of power than can be provided by the power supply,and (iii) transfer power from the one or more energy wells to a powercable electrically positioned between the one or more energy wells andthe power supply when a command is received directing the network to doso.
 13. The network of claim 12, wherein each of the one or more energywells is a modular format battery pack associated with two or more of(i) the window controller, (ii) a control panel, (iii) a trunk line thatconnects two or more of the window assemblies to the control panel or(iv) a drop cable of the network that connects the window controller tothe trunk line.
 14. The network of claim 12, wherein at least one of theone or more energy wells device is included in a respective windowassembly.
 15. The network of claim 12, wherein the energy well isintegrated into the respective window assembly.
 16. The network of claim12, wherein at least one of the one or more energy wells includes atleast one of a battery and a supercapacitor.
 17. The network of claim12, wherein at least one of the one or more energy wells includes amodular format battery pack.
 18. The network of claim 17, wherein themodular format battery pack is configured for installation into a trunkline or drop cable.
 19. The network of claim 12, wherein at least one ofthe one or more energy wells has an energy storage capacity sufficientto simultaneously drive an optical transition in at least two windowassemblies on the network.